Commutator construction for electric machines



June 1931- c. w. LANDERS ,180

COMMUTATOR CONSTRUCTION FOR ELECTRIC MACHINES Filed Oct. 26. 1928 Patented June 23, 1931 p I UNITED STATES PATENT OFFICE' CLYDE LAN'DERS, OF NEW YORK, N. Y.

COMMUTATQR CONSTRUCTION FOR ELECTRIC MACHINES Application filed October 26, 1928. Serial No. 315,262.

This invention relates to improvements in winding are then soldered to the exposed the construction of commutators for electric copper thimbles on the side opposite the carmachines. bon segment.

One object of this invention is an improved The carbon segments are separated from commutator. each other slightly forming an air gap Another object of this invention is to prowhich also produces a slight circulation of the vide suitable resistance in the circuit during air in the motor due to the fan effect. the period when the armature coils are short Standard practice has long been to provide circuited by the brushes. a copper commutator with carbon or similar Another object of this invention is to probrushes in contact with it that wear away vide a commutator and brush arrangement faster than the commutator, thus causing frethat will have unusually long life and keep quent renewal of the brushes. With my imclean. proved construction it will be noted that the Another object of this invention is to procarbon segments of the commutator are sub- 15 vide an armature and commutator construcject to Wear only a small part of the time, or tion in which the commutator can be easily while passing in contact with the copper shoes and practically renewed when necessary. that function the same as brushes.

Another object of this invention is to elim- Special attention is called to the fact that inate the use of copper and mica in c0mml1- although I use carbon and copper in combi- 20 tatcr construction. nation with each other, to secure commuta- Another 'object of this invention is to protion which is old in the art, by rearranging vide a commutator that will not short circuit these two elements as shown in the drawings, the armature coils and burn them. new and better results are secured and the life Another object of this invention is to proof the elements greatly increased.

25 vide a commutator and brush construction in This, construction eliminates practically which the carbon or soft element revolves and all brush and commutator trouble that has alis subject to wear only a portion of the time, ways existed in electric machines, and prowhile the copper or hard element is stationlongs the life of these elements almost inary and is subject to Wear all the time. definitely.

30 In accordance with this invention, the com- In the drawings, comprising but a single mutator is made in the form of a disc, comsheet, five figures, one form of my improved posed of a metal frame firmly mounted on commutator construction is set forth. the armature shaft, and the frame supports Figure '1 isa front view of a commutator a suitable washer made of any insulating showing one form of my invention.

35 material, but preferably a material known Figure 2 is a view partly in section taken as transite a heat resisting composition. through the shaft centre.

Near the periphery of this transite Figure 8 is a front and side view of the washer is a series of holes in which are incarbon segments of the commutator.

serted the rounded portion of the carbon seg- Figure l is a front and side view of the ments which form the commutator. In orcopper thimble.

der to connect the armature conductors to the Figure 5 is a front view of a flat spring carbon segments thin copper thimbles or joined with one of the copper shoes. strips are first inserted in the holes, and the Referring to the drawings, 1 is the armacarbon then forced tightly into the copper ture shaft of a machine, 2 is a metal frame 45 thimbles. The wire leads from the armature that supports the commutator elements, 3 is a washer of insulating materiah such as transits, 4 and 4' are the carbon segments of the commutator, 6 and 6 are the copper shoes that function as brushes, 7 shows the copper strips that form thimbles around the circular portion of the carbon segments. 8 is the armature winding or coils, 9 is the armature core, 10 shows the lead wires from the armature winding to the commutator seg ments, 11 and 11 are flat springs that hold the copper shoes in contact with the carbon segments, 12 shows the soldered connections to the thimbles In the construction of-the prior art wherein a commutator made up of copper segments was employed the armature coils are momentarily short-circuited every time adjacent copper segments are bridged by the carbon brush; the'resistance of the commutator segments is negligible and the current flowing in the short-circuited coil has an appreciable value. When however, the bridged segments are composed of carbon, the resistance of the circuit including the armature coil and the bridging brush is appreciably greater owing to the high specific resistance of carbon, hence the current flowing in the short-circuited coil is much lower in value, thus increasing the useful life of the segments by tending to reduce sparking at the moment the circuit including the bridging brush is opened by the continued rotation of the commutator segments, as well as increasing the useful life of the armature by decreasing the risk'of burning out the armature coils.

The elimination of mica as an insulating medium between the commutator segments is also beneficial as the tendency for the mica to become embedded in the surface of the brush is avoided thereby eliminating pitting of the commutator segments and poor commutation arising from the presence of mica. upon the contacting surface of the brush.

Having thus described my invention, I claim:

1. In a commutator for a dynamo-electric machine and in combination an insulating disc, and a plurality of segments of non-me-- tallic conductive material secured in fixed relation to said disc to define a ring of electrically separated segments the separations between said segments constituting channels for the free (passage of air when the commutator 1s rotate 2. In a commutator construction and in combination a heat resisting insulatin disc, a plurality of segments of non-metallic conductive material, and an ual number of metallic holders for indivi ually securing said segments in fixed relation to said disc to define a ring of electrically separated segments the separations between said segments constituting channels through which the air is fiee to pass when the commutator is rotate York and State of New York this 25th day of October A. D. 1928.

CLYDE W. LANDERS. 

